I was reading today about how Linux Mint developers altered the Banshee music player source code to redirect affiliate revenue from Amazon music orders to them instead of Banshee. They've reportedly made less than $4, which has caused a kerfluffle among those paying attention to that corner of the world. But it raises a larger point that has been swirling around for a couple of decades: an OS vendor has a lot of power to influence, and even monetize their user base. Where should they draw the line?

Well, if you take a definition out of context you are right.
But let's be honest here, when people talk about censoring the internet they talk about changing the rules and currently all rules are already against child porn, because it highly illegal everywhere, so no more rules needed IMO.
And your China analogy is not what I am talking about. I was talking about a law that the whole world agrees on. I don't think Chinas great firewall has that kind of backing.